The invention relates to a high-speed milling or drilling heads with a holder adjustably mounted in it for reversible cutting inserts which contain at least one clamping indentation in each of two parallel top surfaces.
Milling or drilling heads are increasingly being equipped with reversible ceramic cutting inserts to as to make full use of the inserts at the high cutting speeds which these cutting inserts permit. Combined with a specific cutting edge design, these high cutting speeds result in surfaces which are nearly as good as ground surfaces, so that machining with ceramic cutting inserts, and to a limited extent also with metal carbide cutting inserts, makes it possible to eliminate one operation.
On account of the high rotatory speeds and the resultant high circumferential speeds, the clamping means must satisfy stringent requirements, since the secure seating of the cutting insert in the clamping means is no longer assured, on account of the centrifugal forces that are produced. In the case of wheel mills, therefore, use has been made, as disclosed in DE-GM 85 03 545, of perforated cutting inserts of conventional type, which have in the center of their adjacent free surface a perforation which is provided with a recess which is engaged by the clamping means and exercises a pressure against the surfaces of the seat of the insert on the wheel body. Aside from the fact that the required stability, especially at high rotatory speeds, and when the cutterhead comes in contact with the workpiece, is not provided, these perforated cutting inserts have a greater tendency to crack. In DE-GM 85 27 925, therefore, it is proposed to provide a clamping indentation on one side in the cutting insert, the indentation having a trapezoidal shape in longitudinal section and a triangular shape in cross section, or is disposed in the form of truncatoconical countersink. This clamping indentation too is disposed in the adjacent surface, which has the size necessary for the purpose. The depth of the indentation in this case corresponds substantially to half the thickness of the cutting insert.
DE-OS 25 49 757 discloses a wheel mill in the form of a copying cutterhead which consists of a plurality of disks, in which the disk recesses disposed therein serve each to accommodate a reversible cutting insert and a clamping body. The reversible cutting insert can be a perforated cutting insert and in this case is secured by a setscrew which enters into the central hole in the clamping plate, but recesses can also be created in the top surfaces of the reversible cutting insert so as to be engaged by the projections of the clamping wedge and of the disk recesses, respectively. Adjustment of a cutting insert of this kind is not possible, since it does not have a separate holder which can be adjusted in the cutterhead.
In cutterheads which are designed for planing, and boring cutterheads designed for spindling out, the requirements are completely different from those of wheel mills, i.e., the cutting inserts have adjacent free surfaces whose dimensions are insufficient for clamping and in which no depressions can be created to accommodate clamping elements without the danger of damaging the cutting edges.